An arrangement in which, in order to electrically connect a positive electrode and a negative electrode of each battery of a battery assembly having a plurality of batteries and a plurality of interbattery plates alternatingly superimposed, a positioning boss provided on the interbattery plate is fitted into a positioning hole formed in a bus bar plate having a plurality of bus bars to thus position the bus bar plate with respect to the interbattery plate, ease of assembly of the bus bar plate onto the interbattery plate being enhanced by making the diameter of the positioning hole larger than the diameter of the positioning boss, is known from Patent Document 1 below.